1. Field of the Invention
The present invention relates to a liquid crystal display device having pixels equipped with first sub-pixels and second sub-pixels whose pixel electrodes are separated from each other.
2. Description of the Related Art
With conventional liquid crystal display devices, a voltage is applied to a liquid crystal through switching devices such as thin film transistors (TFT) and others disposed in pixels.
FIG. 20 is a view schematically showing a pixel 300 of a conventional liquid crystal display device. A pixel electrode (Pix) 301 is charged to a source potential via a transistor 302. A common voltage (Vcom) is applied to a common electrode (COM) 303, and the potential difference between the common electrode 303 and the pixel electrode 301 is applied to the liquid crystal as a voltage (Vlc). In this case, the liquid crystal sandwiched by the common electrode 303 and the pixel electrode 301 forms a liquid crystal capacitance Clc, whereas a solid dielectric material sandwiched by the pixel electrode 301 and an auxiliary capacitance line 305 forms an auxiliary capacitance Ccs.
The auxiliary capacitance Ccs is formed in parallel with the liquid crystal capacitance Clc. At the same time, since the auxiliary capacitance line 305 is connected in a way that allows the same potential as the common electrode 303 to be applied, the potential fluctuation that occur at the pixel electrode 301 due to a gate potential fluctuation or the leak current at off state of the transistor 302 is reduced. To prevent an image burn-in and electrolysis of the liquid crystal, the liquid crystal display device is ac-driven that the polarity of the voltage is applied to the liquid crystal to be switched at specified intervals.
There is a well-known technique, for example, that a pixel of a liquid crystal device is divided into multiple regions and different voltages are applied to each region to decrease the dependence of display status on viewing angles, as disclosed by Japanese Patent Laid Open Applications, JP H7-028091A (1995) and JP H8-015723A (1996).
Specifically, JP H7-028091A discloses a liquid crystal display device that a TFT is connected to any one of the divided pixel electrodes, and effective voltages at various levels are applied to multiple regions within the pixels of the liquid crystal by applying the voltage to the pixel electrode connected to the TFT to other pixel electrodes via a capacitance formed between the relevant pixel electrode.
JP H8-015723A discloses an active matrix liquid crystal display that its common electrode is disposed opposite to a pixel electrode connected to a TFT and is divided into multiple regions. By applying different voltages to each region, effective voltages at various levels are applied to the liquid crystal of a plural region in a pixel.
However, in the liquid crystal display device disclosed by JP H7-028091A, if the capacitances formed between the pixel electrode connected to the TFT and other pixel electrodes vary due to the difference in thickness of dielectric material (insulation film) for example, a problem arises that the viewing-angle dependences vary among plural liquid crystal display device from device.
On the other hand, in the active matrix liquid crystal display disclosed by JP H8-015723A, since electrode patterning on the pixel size level must be performed on both substrates constituting a liquid crystal panel, it increases the number of manufacturing processes. Furthermore, since high laminating accuracy is required in laminating two substrates, thus inducing a problem that the yielding was lowered.